Development of a frequency-stabilized compact light source for an optically pumped Cs frequency standard

A compact light source using a laser diode, whose frequency was stabilized to a saturated absorption spectrum of the Cs-D2 line (λ=852 nm), was developed for use of an optically pumped cesium frequency standard. The temperature of the laser diode was stabilized within 0.1 mK by two stages of feedback systems. Frequency stabilization to the saturated absorption spectrum was performed by modulating the injection current to the laser diode with 100 kHz. The frequency stability was measured by taking the beat of two light sources thus stabilized, and it was estimated to be 4.4×10−11(15 kHz) at an averaging time of 600 ms.